English

Lomonosov's theorem cannot be extended to chains of four operators

Functional Analysis 2007-05-23 v1

Abstract

We show that the celebrated Lomonosov theorem cannot be improved by increasing the number of commuting operators. Specifically, we prove that if T is the operator on l_1 without a non-trivial closed invariant subspace constructed by C.J.Read, then there are three operators S_1, S_2 and K (non-multiples of the identity) such that T commutes with S_1, S_1 commutes with S_2, S_2 commutes with K, and K is compact. It is also shown that the commutant of T contains only series of T.

Keywords

Cite

@article{arxiv.math/9809100,
  title  = {Lomonosov's theorem cannot be extended to chains of four operators},
  author = {Vladimir G. Troitsky},
  journal= {arXiv preprint arXiv:math/9809100},
  year   = {2007}
}

Comments

5 pages, to appear in Proceedings of the AMS

R2 v1 2026-07-22T18:00:01.392Z